The invention relates generally to the field of spintronics. In particular, it relates to devices and methods relying on non-linear spin-orbit interactions to enable functionalities such as current-to-spin conversion and amplification of spin-polarization.
Spintronics is a field of electronics where the spin-momentum of a charge carrier is used in addition to its charge to generate or process signals. Signals can be processed in terms of communication, storage, sensing or logic applications.
A number of concepts have been proposed that are based on the electron spin. In particular, spin devices have been proposed, which include a spin transport layer (or STL) above a substrate. Connected to the STL are input and output electrodes. The input electrodes act as spin injection contacts and consist of a magnetic material that is magnetized into one of two possible directions (spin up/down). By passing a current between the input electrodes and the STL, spin-polarized electrons can be accumulated in the STL at the interface between the input electrode and the STL. The spin polarization of electrons at that location in the STL is directly related to the magnetization of the input electrode, i.e. the spins in the STL are also either up or down. The output electrodes convert the local spin polarization at the interface between the STL and the output electrode. Spin polarization can, e.g., be converted into an electrical signal. The concepts of input and output electrodes acting as spin injection and spin detection contacts are well known. Between the input and output electrodes, the spin polarization imprinted by the input electrode propagates by diffusion or drift.
In addition, logic gates are known, which use majority-logic concepts, where several input electrodes polarize the electron spin in the STL and the output electrode detects the average spin polarization that diffuses from those input electrodes to the output electrode.
As it can be realized, the spin of charge carriers can be manipulated in both ferromagnetic materials and materials enabling spin-orbit interaction. While devices based on ferromagnetic materials are well established in today's technology landscape, spin-orbit coupled systems are still lacking some basic functionality.